Blood sampling system

ABSTRACT

An apparatus for sampling blood through an intravenous or intraarterial tube which does not interfere with normal operation of an infusion operation or a direct pressure monitoring operation. A needleless sampling site at which fluid can be removed is connected to the tube. A chamber is provided which is connected to the tube such that fluid can be interchanged between the tube and the chamber. A plunger is provided for drawing the fluid from the tube into the chamber and for expelling the fluid from the chamber into the tube. In its normal position, the plunger blocks the interconnection between the tube and the chamber. When in its sampling position, the plunger creates a vacuum in the chamber causing the fluid in the tube to be aspirated into the chamber. The aspirating action causes fluid in the patient to be drawn up to the sampling site. An actuator, which can be operated by a single hand of a medical practitioner, imparts an appropriate feel to the system operation. A practitioner can carefully control the aspiration and expulsion operations of the system due to the resistance provided against the practitioner&#39;s hand movements and configuration of the body and the actuator means. The movement of the plunger is such that fluid is selectively drawn into and expelled from the chamber.

BACKGROUND

1. The Field of the Invention

This invention relates to medical devices used to repeatedly obtainblood samples from a patient by way of an indwelling infusion line.

2. The Background Art

In many cases, the condition of a patient requires that anintravenous/intraarterial tube or catheter be inserted into a bloodvessel. The patient's blood vessel is connected by the tube to a sourceof fluid which provides fluid such as a medicament, and which is alsoconnected to a pressure transducer which senses the pressure within thepatient's blood vessel.

In critical care situations, it is necessary to periodically obtainsamples of the patient's blood. Importantly, each procedure carried outusing a needle stick increases the likelihood of a health care workerbeing inadvertently stuck and thereby being infected from a contaminatedneedle. Rather than stick a patient with a needle each time blood mustbe drawn, it is preferred that blood be drawn through the tube alreadyconnected to the patient's blood vessel. Since the tube connected to thepatient's blood vessel contains fluid other than blood, such as salinesolution and some medication, it is necessary to draw the patient'sblood up into the tube so that a blood sample can be obtained which issubstantially unadulterated by the fluid which is being supplied to thetube by an external source. Once substantially unadulterated blood hasbeen drawn up the tube to a sampling site, the blood sample can becollected into a sample container.

Several devices have been proposed to draw blood up the tube connectedto a patient's blood vessel to a sampling site. All of the proposeddevices utilize a vacuum creating structure in communication with thetube to draw blood out of the patient's blood vessel up to, and past, asampling site on the tube. Disadvantageously, many of the previouslyavailable devices require two-handed operation by a medicalpractitioner. Some of the previous devices utilize a conventionalmedical syringe to create the suction necessary to draw the blood up thetube. Such syringes are often unwieldy to use and their typical long,narrow dimensions makes them cumbersome. Many of the previouslyavailable devices are complicated and expensive. Moreover, some of thepreviously available devices include sharp bends in the fluid pathand/or relatively long supplementary fluid paths both of which result inresidual blood and fluid remaining in the fluid path which can causeproblems such as clotting.

In view of the forgoing, it would be an advance in the art to provide ablood sampling system which overcomes the difficulties and disadvantagespresent in the previously available devices.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION

In view of the above described state of the art, the present inventionseeks to realize the following objects and advantages.

It is a primary object of the present invention to provide a patientfluid sampling system which is compact and convenient to operate.

It is also an object of the present invention to provide a bloodsampling system in communication with a patient's blood vessel which canaspirate blood up to a sampling site with the medical practitioner usingnot more than one hand.

It is also an object of the present invention to provide an in-lineblood sampling system which is reliable and inexpensive to manufacture.

It is a further object of the present invention which minimizes the riskof infection due to operation thereof.

It is a further object of the present invention to provide a bloodsampling system which provides appropriate resistance and sensation forthe medical practitioner using the system.

These and other objects and advantages of the invention will become morefully apparent from the description and claims which follow, or may belearned by the practice of the invention.

The present invention provides a system and method for sampling a bodyfluid through an infusion tube attached to a patient's body. The systemis particularly adapted for use with a tube which is connected to apatient, such as patient's blood vessel, which is infusing a fluid intothe vessel, for example from an infusion device and/or which isconnected to a pressure transducer. When a blood sample is not beingobtained, the sampling system allows an infusion operation and/or adirect pressure monitoring operation to be carried on unaffected.

The preferred embodiments of the present invention include a samplingsite connected to the tube at which fluid can be removed from the tube.The preferred sampling site is a needleless sampling site. A chamber, ormeans for forming a chamber, is provided. The chamber is preferablyformed within a body fabricated from a clear plastic material suitablefor medical applications. The tube connected to the patient has accessto the chamber via a means for connecting the chamber to the tube suchthat fluid can be interchanged between the tube and the chamber.

A plunger or plunger means is also provided. The plunger functions toalter the size of the chamber so that fluid is drawn from the tube intothe chamber and also the fluid is expelled from the chamber into thetube. In some preferred embodiments, a means for actuating the plungermeans is also provided. In its normal position, the plunger minimizesthe size of the chamber. When actuated to a sampling position, theplunger creates a vacuum in the chamber causing any fluid in the tube tobe aspirated into the chamber. The aspiration action causes fluid in thepatient to be drawn up into a sampling site. The plunger is providedwith a resilient tip which slidably engages the side of the chamber.

The apparatus desirably provides operating characteristics which impartan appropriate feel to the system when it is handled and used by amedical practitioner. A medical practitioner can operate the aspirationand expulsion features of the system with only a single hand, ifdesired. Moreover, a medical practitioner can carefully control theaspiration and expulsion operations of the system due to the resistanceprovided against the practitioner's hand movements and the configurationof the apparatus.

Advantageously, in one preferred embodiment of the inventions aperpendicularly to the chamber, passes through the apparatus body, andincludes a means for receiving a portion of a user's hand. The actuatorextends outwardly from the chamber only a short distance. A means isprovided for translating the force applied by the user's hand in adirection substantially perpendicular to the chamber into movement ofthe plunger means such that fluid is selectively drawn into and expelledfrom the chamber. In other embodiments of the invention the plunger andthe body are positioned within a housing so that as the body and theplunger cooperate to increase or decrease the size of the chamber whilethe overall length of the apparatus remains within the length of thehousing.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to better appreciate how the above-recited and other advantagesand objects of the invention are obtained, a more particular descriptionof the invention briefly described above will be rendered by referenceto specific embodiments thereof which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments of the invention and are not therefore to be consideredlimiting of its scope, the invention will be described and explainedwith additional specificity and detail through the use of theaccompanying drawings in which:

FIG. 1 is a perspective view of a first presently preferred embodimentof the present invention.

FIG. 2 is an exploded perspective view of the embodiment illustrated inFIG. 1.

FIG. 3 is an elevational cross sectional view of the embodimentillustrated in FIG. 1 in a first operational position.

FIG. 4 is an elevational cross sectional view of the embodimentillustrated in FIG. 1 in a second operational position.

FIG. 5 is a diagrammatic representation of the embodiment of the presentinvention including a needleless blood sampling site and other fluidinfusion structures.

FIG. 6 is an exploded perspective view of a second presently preferredembodiment of the present invention.

FIG. 7 is an elevational cross sectional view of the embodimentillustrated in FIG. 6 in a first operational position.

FIG. 7A is a cross sectional view taken along line 7A--7A of FIG. 7.

FIG. 8 is an elevational cross sectional view of the embodimentillustrated in FIG. 6 in a second operational position.

FIG. 9 is a diagrammatic representation of the second embodiment of thepresent invention including a needleless blood sampling site and otherfluid infusion structures.

FIG. 9A is a diagrammatic representation of the second embodiment of thepresent invention being operated to withdraw a sample of blood.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made to the drawings wherein like structures willbe provided with like reference designations.

Reference will first be made to FIG. 1 which is a perspective view of afirst presently preferred embodiment of the present invention. The bloodsampling system illustrated in FIG. 1, generally indicated at 100, ispreferably placed in-line with a catheter used for pressure sensing orin-line with an intravenous infusion device. The blood sampling system100 can be connected to other medical devices as known in the art and asexplained herein. While the structures of the present invention areparticularly adapted for use with sampling blood, it will be appreciatedthat the present invention can be used to sample other fluids,particularly biological fluids which are found in a patient'scirculatory system, and this is to be understood whenever the term"blood" is used herein.

The blood sampling system 100 comprises a body, generally indicated at102, which includes a base 102A having two slots 102C used for securingthe base 102A to another object. For example, the base 102A may receivea strap (not illustrated) which wraps around an adjacent object, such asa pole or a patient's arm.

A chamber housing 102B is also part of the body 102. The base 102A andthe chamber housing 102B are preferably fabricated as a single injectionmolded piece using a clear plastic material as known in the industry.All of the described components of the blood sampling system 100 arepreferably fabricated from clear materials so that any bubbles presentin the fluid can be observed. Desirably, the structure of the bloodsampling system 100 of the present invention minimizes the creation ofbubbles. A tube 104 leads to the patient (usually to an indwellingpatient catheter represented in FIG. 5 at PC) and to a blood samplingsite (represented generally at 156 in FIG. 5) at which blood will becollected. A tube 106 leads to a source of fluid (FS in FIG. 5) and to apressure transducer (PT in the FIG. 5). A cap 130 is provided on the topof the body 102.

Reference will now also be made to FIG. 2 which is an explodedperspective view of the embodiment illustrated in FIG. 1. As can be seenin FIG. 2, two openings 166 are provided in the wall of the body 102. Anactuator 122 is configured to slidably rest within the openings 166 sothat the actuator 122 passes through the body 102 (as also illustratedin FIG. 1). The actuator 122 is provided with an actuator slot 126.

As shown best in FIG. 3, a plunger 128 is disposed within the body 102.The plunger 128 is generally cylindrical and is sized to substantiallymatch the inner diameter of the body 102. A tip 114 is provided on theplunger 128. The tip 114 is preferably fabricated from a resilientmaterial as is available in the art.

A fin 118 is provided on the upper side of the plunger 128. An inclinedslot 120 is provided in the fin 118. A fin guide, shown in the cutawayportion of FIG. 2 at 131, is formed on the underside of the cap 130. Thefin guide 131 is configured to receive the fin 118 therein as the fin118 moves as will be explained shortly. The thickness of the fin 118 ispreferably selected so that it closely fits within the actuator slot126. When the blood sampling system 100 is assembled, the fin 118 isheld captive within the actuator slot 126 and a rod 124 is placedthrough bores 125 provided in the actuator 122 and through the inclinedslot 120. The rod 124 is preferably cylindrically shaped and is held inplace in the bores 125 so that the rod 124 can slide along the inclinedslot 120 to cause the movement of the plunger 128 within the body 102.It will be appreciated that the described structures are to befabricated such that they withstand the pressures which will beencountered during use.

As will be explained further shortly, the actuator 122 and the body 102together provide a structure which is comfortable, convenient, andefficient for a medical practitioner to operate for drawing blood up thetube 104 (FIG. 1) when desired to collect a blood sample. When it isdesired to operate the blood sampling system 100, the medicalpractitioner pushes against the end of the actuator, most desirably witha thumb, finger, or palm of the hand, while also grasping the body 102and/or the cap 130 with one or more fingers of the same hand. Thisadvantageously allows efficient one-handed operation of the bloodsampling system 100 in a manner not possible prior to the presentinvention.

The cross sectional views of FIGS. 3 & 4 will be referred to next tofurther explain the structure of the blood sampling system 100 and theadvantageous operation thereof. As seen in FIGS. 3 & 4, the cap 130 isprovided with an inner rim 136 which engages a ridge 138 on the upperend of the body 102 to hold the cap 130 in place on the body 102. Aninner lip 132 extends from the lower side of the cap 130 and forms arecess with an outer lip 134 into which the wall of the chamber housing102B is received. The plunger tip 114, shown in cross section, makes aslidable, fluid-tight engagement with the interior wall 102D of the body102. The plunger tip 114 is held in place on the plunger 128 by aretaining ring 116.

The blood sampling system 100 is represented in its normal position inFIG. 3. In the normal position, a substantially uninterrupted passageway108 is formed between tube 104 and 106. In the normal position, normalfluid communication occurs between the patient (connected to tube 104)and the medical apparatus, such as a pressure transducer or intravenousfluid pump (connected to tube 106) as if the blood sampling system 100was not present. Furthermore, the embodiments of the present inventionavoids the problems which occur when the blood/fluid mixture is requiredto negotiate sharp bends or a long supplementary fluid path. Moreover,when in the normal position, the embodiments of the present inventiondescribed do not dampen the frequency response discerned by any pressuretransducer being used.

As known in the art, in order to obtain a blood sample, the tube 106 isblocked (for example clamped or stopped) and a vacuum is created toaspirate the fluid contained in the tube 104 into the body 102 causingthe patient's blood to be drawn up into the tube 104 so thatunadulterated blood reaches a sampling site. FIG. 5 provides a schematicdiagram of the blood sampling system of the present invention which isconnected to a stop cock 152 and a needleless blood sampling device 156which functions as a sampling site. Optionally, in accordance with thepresent invention, the tube 106 may be left open (rather than being,clamped or stopped) and satisfactory aspiration of blood will occur. Theneedleless blood sampling device 156 works in cooperation with a samplecontainer (not represented in FIG. 5), generally in the form of asyringe which can be readily attached and remove and which is configuredto withdraw a blood sample from the needleless blood sampling device156. In practice, the blood sampling system must provide unadulteratedblood at the position of the needleless blood sampling device 156. Thatis, the blood must not be substantially mixed with any infused fluid orother fluid which may otherwise normally be present in the tube 104.

Referring now to FIG. 3, to obtain a blood sample, a practitioner pushesthe actuator in the direction of arrow 140. As the actuator is moved inthe direction of arrow 140, the rod 124 is also moved. Since thecombination of the plunger 116 and the fin 118 are held captive by thechamber housing 102B, the actuator slot 126, and the fin guide 131, asthe rod 124 moves within the inclined slot 120 in the direction of arrow140, the plunger 116 and the plunger tip 114 is moved upward in thedirection of arrow 142 creating a chamber in communication with thepassageway 108 as represented in FIG. 4.

As the actuator is moved by the medical practitioner, the structuresdescribed herein provide a suitable resistance to the pressure exertedby the medical practitioner. Such resistance provides the medicalpractitioner with a desirable feel and sensation when operating theblood sampling system and allows the practitioner to accurately controlthe rate at which the actuator 122 is moved. Moreover, as one end of theactuator 122 is pushed by the practitioner, the other end of theactuator 122 extends further from the body 102. In this way, thepractitioner gains further control over the operation of the bloodsampling system 100 by placing one portion of the practitioner's hand(e.g., a palm) on one end of the actuator 122 and another portion of thepractitioner's hand (e.g., a middle finger) on the other end of theactuator.

The described structures of the blood sampling system also provides thatthe plunger substantially remains in whatever position it is found atwhen the practitioner ceases to push on the actuator 122. Thus,advantageously, there is no need for an additional locking mechanism tolock the plunger in its normal position, or in any other position.Moreover, the volume of the chamber created when the plunger is in theposition represented in FIG. 4 is great enough to accommodate enoughblood and other fluid mixture so that the blood which is drawn up fromthe patient's blood vessel to the sampling site (the needleless bloodsampling device 156 in FIG. 5) is substantially unadulterated. Forexample, the volume of the aspiration chamber of the embodimentsdescribed herein can be at least 10 cc for applications involving adultsand at least 1 cc for applications involving neonates. Other volumes canalso be used within the scope of the present invention.

Referring again to FIG. 4, once the blood sample has been obtained, thepractitioner pushes the actuator 122 in the direction of arrow 144 whichcauses the plunger 116 and the plunger tip 114 to move in the directionof arrow 146. Advantageously, the movement to expel is merely thereverse of the convenient movement to aspirate and the movement has thesame desirable characteristics in both directions. The movement of theplunger 116 expels the contents of the chamber back into the passageway108 and the plunger assumes its previous position illustrated in FIG. 3.The blood sampling system 100 functions reliably for one hundred or moreaspiration and expulsion cycles.

It will be appreciated that the mating relationship between the bottomof the plunger tip 114 and the conical surface 102E of the chambershould be selected so that the contents of the chamber are expelled ascompletely as possible. While complete expulsion of the contents may notbe practical in all circumstances, the residue which remains should beminimized so that clotting and other difficulties are minimized. Whenfabricating the conical surface 102E and the plunger tip 114considerations such as the material and hardness of the plunger tip 114,matching or mismatching of the angles of the conical surface 102E andthe surface of the plunger tip 114, and the thickness of the plunger tip114 material, should all be considered. It is within the scope of thepresent invention to fabricate the angle of the conical surface 102E andthe angle of the plunger tip surface 114 so that the anglessubstantially match, so that the angles are substantially different, andso that the angles vary along the their surfaces.

As can be seen best in FIG. 4, the embodiments of the present inventionadvantageously minimizes the possibility of contamination of thepatient's blood and infused fluids with contaminants from thesurrounding environment. Desirably, the wetted surfaces of the bloodsampling system cannot come into contact with the medical practitionerduring use. Airborne contamination is also minimized since air flow intothe chamber is restricted and any airborne contaminants which aredeposited on the inner wall of the body 102D are wiped by the plungertip 114. It is also within the scope of the present invention to utilizea flexible covering over one or more portions of the blood samplingsystem 100 to completely isolate the wetted surfaces from airbornecontaminants.

FIG. 5 provides a schematic representation of an embodiment of thepresent invention with additional exemplary components which arecommonly used in patient care applications. A blood sampling device 300is represented with the tube 106 leading in the direction of arrow 164to, for example, a pressure transducer PT and an infusion device actingas a fluid source FS. A clamp or stop cock structure 208 is preferablyprovided along the tube 106 for imposition during aspiration of blood.As mentioned earlier, by proper selection of the components shown inFIG. 5, and their relative positions, the stop cock 208 structure neednot be operated during the sampling of blood. A tube 104 leads to afitting 150 to which a stop cock 152 is preferably attached.

A needleless blood sampling port 156 is provided with fittings 154 and158. The needleless blood sampling port 156 is preferably one availablein the art from Migada, Inc. under the trademark LAB-SITE but otherstructures can also be used as a sampling site. A fitting 160 connectsto tubing which leads to the patient in the direction of arrow 162. Itis to be understood that many additional and/or alternative structurescan also be included in embodiments of the present invention.

Reference will next be made to FIGS. 6-9 to describe the structure andoperation of a second presently preferred embodiment of the presentinvention. FIG. 6 will be referred to next to provide an overalldescription of the structure and operation of the second presentlypreferred embodiment of the present invention generally indicated at200.

FIG. 6 is an exploded perspective view of the second presently preferredembodiment 200 illustrating the components thereof ready to beassembled. Illustrated in FIG. 6 is a shroud generally represented at202. A plunger is also generally represented in FIG. 6 at 204 with aplunger tip being generally represented at 206 in FIG. 6. A body,generally represented at 208, and an end cap, generally represented at210, are also illustrated in FIG. 6. Further information regarding thestructure, assembly, and the operation of these components will beprovided hereafter.

As explained earlier, the rigid components of the preferred embodimentsare preferably fabricated from a clear plastic material suitable formedical applications. Desirably, the pertinent components aresubstantially visually transparent so that bubbles, clots, and otherabnormalities within the fluid can be observed by a medicalpractitioner.

The shroud 202 preferably comprises a cylindrical receptacle 213. Itwill be appreciated that the shroud 202 functions as a housing for theplunger 204 and the body 208. Advantageously, as will be furtherexplained shortly, the linear motion of the body 208 is limited to thelength of the shroud 202. A concentric circle knoll 212 is preferablymolded into the closed end of the shroud 202 as an indication to themedical practitioner where to place a thumb, finger, or palm duringoperation. An opening 214B is one of two openings (opening 214A isrepresented in FIGS. 7 and 8) which receive prongs 224A&B on the plunger204. During assembly of the apparatus, it is preferred that the prongs224A&B travel up tapered grooves, one of which is represented at 216,formed on the interior of the cylindrical receptacle 213 until theprongs 224A&B are received into their respective openings 214A&B. Theplunger 204 is thus held in place in the interior of the cylindricalreceptacle 213.

Also provided in the cylindrical receptacle 213 are two slots 218A(illustrated in FIG. 7 & 218B) which receive the teeth 250A&B,respectively, in a locking engagement as will be explained furthershortly. Also included in the cylindrical receptacle 213 are twocutouts, one shown in the perspective view of FIG. 6 at 220B and anotherat 220A in the cross sectional views of FIGS. 7 and 8. The cutouts220A&B are dimensioned to receive the arms 252A&B included in the body208 in a slidable fashion as will be explained in greater detailshortly.

Also illustrated in FIG. 6 is an opening 222A. The opening 222A is oneof two openings which receive the prongs 260A&B on the end cap 210 thusholding the end cap 210 in place on the shroud 202. A slotted plate 223is provided on the cylindrical receptacle 213. The slotted plate 223 isused to attach the apparatus 200 to the patient via a strap (notillustrated in the figures) or to another structure.

The plunger 204 fits within the cylindrical receptacle 213 of the shroud202. The diameter of a cylindrical base 232 is selected so that when theplunger 204 is held within the cylindrical receptacle 213 a gap existsbetween the circumference of the cylindrical base 232 and the interiorof the cylindrical receptacle 213. The gap is best seen in the crosssectional views of FIG. 8 and is provided to receive a cylindricalvessel 246 included in the body 208.

As shown best in FIG. 6, four legs 226A&B and 230A&B extendperpendicularly from the cylindrical base 232 with each of the legs226A&B and 230A&B preferably being oriented at right angles to eachother. The legs 226A&B are provided with the two prongs 224A&B on theend of tines 224C&D which flex and allow prongs 224A&B to move as theplunger 204 is inserted into the cylindrical body 213 and engage theopenings 214A&B. The legs 230A&B are each provided with a post 228A&B.The posts 228A&B each engage the interior surface of the cylindricalreceptacle 213. The posts 228A&B function to further hold the plunger204 in place and maintain the gap between the legs 226A&B and 230A&B andthe interior of the cylindrical receptacle 213. A retaining disc 234 isprovided on the plunger 204 to hold a plunger tip 206 in place thereon.

The plunger tip 206 is preferably fabricated from a resilient material,for example those materials from which syringe plunger tips arefabricated in the industry. A groove 236 is provided on the interior ofthe plunger tip 206 into which the retaining disc 234 is received. Asseen best in the cross sectional views of FIGS. 7 and 8, the groove 236and retaining disc 234 hold the plunger tip 206 against the base 232.Also as seen best in FIGS. 7 and 8, the plunger tip 206 is provided witha first wiper 239 and a second wiper 238 which are particularlyconfigured to slidably engage the interior surface 246A of thecylindrical vessel 246. The function of the plunger tip 206 will befurther discussed later.

Referring again to FIG. 6, the body 208 includes the cylindrical vessel246 and perpendicularly extending arms 252A&B. The arms 252A&B canpreferably be molded as part of the cylindrical vessel 246. Each of thearms 252A&B includes passageways 256A&B, respectively, each of whichcommunicate with the interior of the cylindrical vessel 246 as seen bestin the cross sectional view of FIGS. 7 and 8. At the ends of each of thepassageways 256A&B are tubing bores 254A&B, respectively, which receivetubing segments 204 and 206, respectively, as represented in FIG. 9. Thetubing segments 204 and 206 are preferably lengths of clear tubinggenerally used in medical applications and are secured to the tubingbores 254A&B in a manner known in the art.

As shown best in FIG. 6, a pair of finger grips 248A&B are each flexiblyattached to the arms 252A&B, respectively. The flexible attachment ofthe finger grips 248A&B to the arms 252A&B (1) allows the teeth tolockingly engage the slots 218A&B when the arms are slid up to theclosed ends of cutouts 220A&B thus locking the shroud 202 and the body208 in a fixed position relative to each other and (2) allows the userto release the teeth 250A&B from the slots 218A&B allowing the shroud202 and the body 208 to move with respect to each other.

As will be further discussed in connection with FIGS. 7 and 8, when thesecond embodiment of the present invention 200 is assembled the plunger204 with the plunger tip 206 are held in the shroud 202 with the body208 also being inserted into the shroud 202 with the plunger 204 and theplunger tip 206 being held captive within the interior of thecylindrical vessel 246. To hold all of these components together intheir proper relationship, an end cap 210 is locked into the open end ofthe shroud 202. The end cap 210 includes a plate 258 from which a pairof posts 261A&B perpendicularly extend. Each of the posts 261A&B areprovided with claws 260A&B (see FIG. 6), respectively, which engageopenings, one of which is represented at 222A, provided in the shroud202. Once assembled, the second embodiment can advantageously beutilized to aspirate and expel fluids as will next be explained.

Reference with next be made to FIG. 7 which is an elevational crosssectional view of the embodiment illustrated in FIG. 6 in a firstoperational position. In the first operational position all of the fluidhas been expelled from the second embodiment 200 and a fluid path hasbeen created between the tubing bore 254A and the tubing bore 254B. Thefirst operational position is also referred to as the normal positionsince it is normal for substantially all of the fluid to be expelledfrom the device except for the fluid which will be described shortly inconnection with FIG. 7A.

In the cross sectional view of FIG. 7, the relationship between theshroud 202 and the body 208 can be observed. In the first operationalposition illustrated in FIG. 7, the cylindrical vessel 246 of the body208 has been pushed as far as possible into the closed end of the shroud202 towards the concentric circle knoll 212. As can be readily observedin FIG. 7, the cylindrical vessel 246 has a diameter which closely fitswithin the interior of the cylindrical receptacle 213 of the shroud 202.

In order to move the body 208 into the first operational position shownin FIG. 7, the user preferably places the first end of the shroud 202having the concentric circle knoll 212 against the thumb or palm of ahand. The user also places a finger on a first finger rest 253A (locatedon one side of the arm 252A) and another finger on a second finger rest253B (located on one side of the arm 252B). With the first end of theshroud positioned against the user's palm or against the user's thumb,and a finger positioned on each of the finger rests 253A&B, the user canutilize a flexion motion of the fingers and/or the thumb (movement ofthe fingers and thumb toward the palm) to move the body 208 against thefirst end of the shroud 202 to the position represented in FIG. 7.

As seen best in the cross sectional view of FIG. 7, the prongs 224A&Bhave been received into the openings 214A&B, respectively, holding theplunger 204 in the shroud 208. The legs 226A&B which support the prongs224A&B are dimensioned such that the plunger fits within the cylindricalvessel 246 as the body 208 moves within the shroud 202. It will beappreciated that the body 208 and the plunger 204 together form achamber and are one preferred arrangement for selectively increasing anddecreasing the volume or size of the chamber which is formed.

As the body moves to the position represented in FIG. 7, the volume ofthe chamber volume created by the wall of the cylindrical vessel 246 andthe first wiper 238 of the plunger 206 is reduced to nearly zero and thefluid contained in the body is expelled through passageways 256A&B. Aflat end 240 provided on the plunger tip 206 makes contact with thefloor 243 of the body 202. As shown in the cross sectional view of FIG.7A (taken along line 7A-7A of FIG. 7), substantially all of the fluid issqueezed out in the area where contact is made between the flat end 240of the plunger tip 206 and the floor 243 of the body 208. Importantly, afluid channel 242 remains to provide a fluid path in the directions ofarrows 264 and between the passageway 256A and passageway 256B.Significantly, using the arrangement represented in the drawing, thereis no backspace where blood can accumulate and coagulate, as withpreviously available devices, when the apparatus is placed in its normalposition.

The fluid channel 242 is configured to allow fluid flow through thechannel 242 as well as allowing pressure pulses to be transmittedthrough the channel 242. FIG. 9 provides a diagrammatic representationof the second embodiment 200 of the present invention including theneedleless blood sampling site 156, the patient catheter PC, thepressure transducer PT, and the fluid source FS. The fluid channel 242(FIG. 7A) must provide suitable fluid flow from the fluid source (FS inFIG. 9) and must accurately transmit pressure pulses from the patientcatheter (PC in FIG. 9) to the pressure transducer (PT in FIG. 9).

The fluid channel 242 is configured to provide a continuous fluid columntherethrough by minimizing obstructions, reducing the formation of gasbubbles, and providing the proper volume of fluid, within the fluidchannel 242 for accurate transmission of pressure pulses therethrough.The configuration of the fluid channel 242 is such that the formation ofclots therein is minimized. The formation of clots within the fluidchannel 242 blocks the desirable flow of fluid therethrough and degradesthe transmission of pressure pulses therethrough. The configuration ofthe fluid path 264 provides a smooth transition between the tubes (204and 206 in FIG. 9) connected to the tubing bores 254A&B so as tominimize the formation of clots and accurately transmit pressure pulsesto the pressure transducer (PT in FIG. 9). Those skilled in the art willappreciate that the materials for the body 208 and the plunger tip 206should be selected from those available in the industry to achieve theenumerated benefits among other desirable characteristics discussedherein.

Reference will next be made to FIG. 8. FIG. 8 is a elevational crosssectional view of the second presently preferred embodiment of thepresent invention in a second operational position. When moved to thesecond operational position in the direction indicated by arrows 249,fluid is aspirated into the cylindrical vessel 246 of the body 208. Inthe arrangement represented in FIG. 9, moving to the second operationalposition causes the fluid to be drawn up from the patient catheter PC tothe blood sampling site 156 such that blood, or other bodily fluid, canbe withdrawn into a sample container (not represented in the figures).

In order to move to the body 208 in the direction of arrows 249 to thesecond operational position represented in FIG. 8, the user preferablyplaces the second end of the shroud 202 having the concentric circleknoll 262 against the thumb of one hand. The user also preferably placesone finger (for example a middle finger) on the finger grip 248A andanother finger (for example a ring finger) on the finger grip 249B. Withthe second end of the shroud 202 and the concentric circle knoll 262positioned against the user's thumb and with a finger positioned on eachof the finger grips 248A&B, the user utilizes a pulling motion to flexthe finger grips 248A&B to release the teeth 250A&B from the slots218A&B, respectively, as shown best in FIG. 7.

The finger grips 248A&B are biased so that they engage the slots 218A&Band lock the body 202 in its normal position illustrated in FIG. 7.Importantly, the device 200 will remain in the normal position most ofthe time during use and the finger grip 248A&B with teeth 250A&Bengaging the slots 218A&B ensures that the device 200 will remain in thenormal position even though the device 200 is inadvertently bumped bythe patient or practitioner or even if the highest expected pressure isintroduced in the fluid channel. Remaining in the normal position isimportant to the convenient and safe operation of the device 200.

With the user's fingers preferably positioned as described, the userpulls in the direction of arrows 249. The pulling action, whichdesirably is the same action as is used to move the device 200 to itsnormal position but applied to the opposite end of the device, causesthe first wiper 240 and the second wiper 238 to slide along the interiorsurface 246A of the cylindrical vessel 246 of the body 208. The fluidtight seal formed between the first wiper 240, the second wiper 238 andthe inner wall 246A cause a vacuum to be developed in the chamber formedby the interior surface 246A of the cylindrical vessel 246 and the firstwiper 238 of the plunger 206. The resulting vacuum causes fluid to beaspirated into the chamber formed in the body 208.

Reference will next be made to FIG. 9 which is a diagrammaticrepresentation of the second embodiment 200 shown in a normal position.In the normal operational position the flow of fluid occurs from thefluid source FS, through the pressure transducer PT and the apparatus200 and the associated tubing and structure, to the patient catheter PC.When it is desired to obtain a blood sample, the practitioner canpreferably grasp the apparatus 200 as illustrated in FIG. 9A. Using twofingers and the thumb of one hand, the body (hidden within the apparatus200 in the view of FIG. 9) is moved to the sampling position shown inFIG. 9A and fluid is aspirated into the chamber formed in the body.

In view of the forgoing, it will be appreciated that the presentinvention provides a patient fluid sampling system which is compact andconvenient to operate and which can aspirate blood up to a sampling sitewith the medical practitioner using not more than one hand. The presentinvention also provides an in-line blood sampling system which isreliable and inexpensive to manufacture, which minimizes the risk ofinfection due to operation thereof, and which provides a blood samplingsystem which provides appropriate resistance and feel for the medicalpractitioner using the system.

These benefits of the present invention are in contrast to thedisadvantages of the previously available devices which require twohands to operate or require awkward motions by the practitioner. Thepresent invention allows sufficiently large volumes to be aspiratedwhile maintaining the apparatus in a small and convenient size. Thepresent invention also avoids contamination of the fluid and allows thepractitioner to use the same motion to return the apparatus to thenormal position as was used to aspirate fluid. Moreover, the fluid pathcreated when the apparatus is in its normal position avoids theformation of clots which would otherwise dampen the pressure waves tothe pressure transducer (PT in FIG. 9) or the flow of fluid to thepatient catheter (PC in FIG. 9). These and other advantages provide ablood sampling system which is more efficient and reliable than thosepreviously available.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed and desired to be secured by United States LettersPatent is:
 1. A system for sampling a body fluid through a conduitattached to a patient's body, the system being operable by a user havinga hand including a palm, a thumb and at least a first finger and asecond finger, the system comprising:a fluid sampling site connected tothe conduit; means for receiving the conduit; means for forming achamber; and means for selectively increasing and decreasing the size ofthe chamber such that the size of the chamber is selectively increasedto a maximum volume and selectively decreased to a minimum volume, themeans for selectively increasing and decreasing the size of the chamberbeing operable by moving the first and second fingers or the thumb in aflexion movement toward the palm to achieve the maximum volume of thechamber, the means for selectively increasing and decreasing the size ofthe chamber also being operable by moving the first and second fingersor the thumb in a flexion movement toward the palm to achieve theminimum volume of the chamber such that the same motion of the user'sfirst and second fingers can selectively accomplish the maximum volumeto create a suction action to aspirate fluid from the patient's body tothe fluid sampling site or accomplish the minimum volume to increasepressure within the chamber to expel the fluid into the patient's body.2. A system as defined in claim 1 further comprising shroud means forcovering the means for selectively increasing and decreasing the size ofthe chamber, the shroud means having a length and the length notchanging as the minimum volume and the maximum volume is achieved.
 3. Asystem as defined in claim 1 wherein the means for forming a chambercomprises a substantially cylindrically shaped body.
 4. A system asdefined in claim 3 wherein the means for selectively increasing the sizeof the chamber comprises:a shroud at least substantially covering thebody; and a plunger attached to one end of the shroud, the plunger beingslidably inserted into the body.
 5. A system as defined in claim 3wherein the body comprises a substantially clear plastic material.
 6. Asystem as defined in claim 3 wherein the body comprises a substantiallyflat bottom and wherein the plunger comprises a tip formed from aresilient material, the tip having a flat surface which mates againstthe flat bottom when the volume of the chamber is minimized, the tipalso comprising a fluid channel formed therein.
 7. A system as definedin claim 6 wherein the fluid channel comprises a circular channel formedabout the perimeter of the tip.
 8. A system for sampling a body fluidthrough a conduit attached to a patient's body, the system beingoperable by a user having a hand including a palm, a thumb and at leasta first finger and a second finger, the system comprising:a fluidsampling site connected to the conduit; means for receiving the conduit;means for forming a chamber; means for housing the means for forming achamber; and means for selectively increasing and decreasing the size ofthe chamber, the means for increasing and decreasing the size of thechamber being positioned within the means for housing and includingmeans for receiving the first finger and the second finger extending outof the means for housing, the size of the chamber being altered as themeans for receiving the first finger and the second finger beinglinearly moved along the length of the means for housing, the pressurewithin the chamber being lowered as the size of the chamber is increasedsuch that the body fluid is sucked in a direction toward the chamber orthe pressure within the chamber is increased as the size of the chamberis decreased such that the body fluid is expelled in a direction awayfrom the chamber.
 9. A system for sampling a body fluid as defined inclaim 8 wherein:the means for housing comprises a shroud and wherein themeans for forming a chamber comprises a body and a plunger; wherein themeans for selectively increasing and decreasing comprises slots formedwithin the shroud wherein the means for receiving the first finger andthe second finger are slidably received and wherein the means forreceiving the first finger and the second finger are attached to thebody.
 10. A system for sampling a body fluid as defined in claim 8wherein the chamber has a volume of at least ten cubic centimeters. 11.A system for sampling a body fluid as defined in claim 8 wherein thesampling site comprises a needleless sampling site.
 12. A system forsampling a body fluid as defined in claim 8 wherein the length of thehousing means is not greater than six inches.
 13. A system for samplinga body fluid as defined in claim 8 wherein the length of the housingmeans is not greater than four inches.
 14. A system for sampling a bodyfluid as defined in claim 8 further comprising:means for receiving fluidfrom a fluid source; and means for forming a fluid path through thechamber from the means for receiving the conduit to the means forreceiving fluid when the size of the chamber is minimized.
 15. A systemfor sampling a body fluid as defined in claim 9 wherein the plungercomprises a flat tip.
 16. A system for sampling a body fluid through atube attached to a patient's body, the system comprising:a sampling siteconnected to the tube; means for receiving the tube; means for forming achamber; means for connecting the chamber to the tube such that fluidcan be interchanged between the tube and the chamber; plunger means fordrawing the fluid from the tube into the chamber and for expelling thefluid from the chamber into the tube; actuator means for actuating theplunger means, the means for actuating the plunger meanscomprising:means, extending outwardly from the chamber, for receiving aportion of a user's hand; means for translating a force applied by theuser's hand in a direction substantially perpendicular to the chamberinto movement of the plunger means such that fluid is selectively drawninto and expelled from the chamber.
 17. A system as defined in claim 16wherein the means for translating comprises:a slot connected to theplunger means and oriented at an angle with respect to the direction oftravel of the plunger; and a rod connected to the actuator means andslidably positioned in the slot.
 18. A system as defined in claim 16wherein the sampling site comprises a needleless sampling port.
 19. Asystem as defined in claim 16 wherein the means for forming a chambercomprises a substantially cylindrically shaped body.
 20. A system asdefined in claim 19 wherein the body comprises a substantially clearplastic material.
 21. A system as defined in claim 19 wherein theactuator means comprises a linearly shaped actuator and the bodycomprises first and second openings through which the actuator passessubstantially perpendicularly to the direction of travel of the plungermeans.
 22. A system as defined in claim 16 wherein the plunger meanscomprises a resilient material formed in a first conical shape andwherein the means for forming a chamber comprises a bottom, the bottomhaving a second conical shape and an aperture at the apex of the conicalshape, the aperture providing fluid communication with the tube.
 23. Asystem as defined in claim 16 wherein the means for forming a chambercomprises a cap covering the chamber.
 24. A system for sampling apatient's internal fluid through a tube connected to a vessel of thepatient, the system comprising:a chamber in fluid communication with thetube, the chamber having an inner wall; a body holding the chamber, thebody having an external side wall; a plunger slidably positioned in thechamber and in contact with the inner wall; an actuator having first andsecond ends, the actuator passing through the body and having a firstposition wherein at least the first end of the actuator extends from thebody and a second position wherein at least the second end of theactuator extends from the body such that a user's hand can applypressure to the actuator when in its first position and in its secondposition such that the user can move the actuator from the firstposition to the second position; means for translating the movement ofthe actuator between the first position and the second position intomovement of the plunger between a first position which decreases thevolume of the chamber and a second position which increases the volumeof the chamber such that movement of the actuator from the firstposition to the second position causes fluid to be drawn into thechamber and movement of the actuator from the second position to thefirst position causes fluid to be expelled from the chamber; and asampling site connected to the tube between the patient's vessel and thechamber, the patient's fluid being drawn from the vessel to the samplingsite as the plunger moves between its first position and its secondposition such that a sample can be withdrawn at the sampling site.
 25. Asystem as defined in claim 24 wherein the means for translatingcomprises:a slot connected to the plunger and oriented at an angle withrespect to the direction of travel of the plunger; and a rod connectedto the actuator and slidably positioned in the groove.
 26. A system asdefined in claim 24 wherein the sampling site comprises a needlelesssampling port.
 27. A system as defined in claim 24 wherein the bodycomprises a substantially cylindrically shaped body.
 28. A system asdefined in claim 24 wherein the body comprises a substantially clearplastic material.
 29. A system as defined in claim 24 wherein theactuator is linearly shaped and the body includes first and secondopenings through which the actuator passes.
 30. A system as defined inclaim 24 wherein the plunger comprises a resilient material formed in afirst conical shape, the chamber having a bottom, the bottom having asecond conical shape and an aperture at the apex of the conical shape,the aperture providing fluid communication with the tube.
 31. A systemas defined in claim 30 wherein the angle of the first conical shapesubstantially matches the angle of the second conical shape.
 32. Asystem as defined in claim 30 wherein the angle of the first conicalshape is different than the angle of the second conical shape.
 33. Asystem as defined in claim 30 wherein the angle of the first conicalshape is greater than the angle of the second conical shape.
 34. Asystem as defined in claim 24 further comprising:a cap over the body;and means for guiding the plunger between the first position and thesecond position.